Decoy flares are countermeasures ejected from an aircraft to mislead a missile's infrared or heat seeking guidance system to target the flares rather than the aircraft. Decoy flares may be categorized as pyrotechnic or pyrophoric. Pyrotechnic flares use a slow burning fuel/oxidizer combination to generate intense heat to attract the missiles. In contrast, pyrophoric flares self-ignite when exposed to oxygen in the air. When the pyrophoric material is ejected from an aircraft, it is designed to flutter in the air due to the high surface area to mass ratio of the pyrophoric material. This allows the pyrophoric material to disperse in a cloud like pattern thereby mimicking an aircraft's fuel exhaust or hot engine components.
Conventional methods for the preparing pyrophoric countermeasures rely on chemical leaching techniques for the formation of high specific surface area metal substrates that are reactive to oxygen. U.S. Pat. No. 4,895,609 issued to Baldi et al, discloses current methods for preparing iron coated on steel pyrophoric materials. The methods generally requires:                a. Mixing iron and aluminum powders in a slurry containing a suitable solvent and binder. Then applying the mix onto a very thin steel foil by dip coating or spraying.        b. The resulting material is heated to 500° C. to evaporate the solvent and binder to yield a coat of metallic powder on the steel foil.        c. The coated substrate is further heated to a high temperature of 800° C. to 1000° C. in a reducing atmosphere such as hydrogen or argon to form an iron/aluminum alloy.        d. The aluminium from the resulting alloy is then leached with highly concentrated, hot sodium hydroxide (NaOH) solution to form highly pyrophoric, porous iron.        
The Baldi method utilizes chemical leaching to prepare porous iron which requires use of high concentrations of hot, corrosive NaOH solution. Handling of such caustic materials increases safety risks to the user as NaOH has been known to cause permanent damage to human tissue. Sodium hydroxide is also designated as a hazardous environmental substance under the Federal Water Pollution Act and Clean Water Act.
U.S. Pat. No. 8,623,156 issued to Haines et al, addresses alternative methods for preparing pyrophoric foils without the use of chemically hazardous materials like NaOH. The patent discloses methods for water based processing followed by hydrogen reduction of iron oxide to form pyrophoric nano-iron on various types of ceramic, metal, and nanomaterial substrates. Similar to Baldi, the Haines' '156 patent also requires an underlying substrate to provide structural integrity to the pyrophoric material.
U.S. Patent application publication number 20060042417 by Gash et al, discloses sol-gel methods to generate high surface area porous iron for making pyrophoric substrates. This method avoids the use of NaOH, however, poor adhesion of the particles to the substrates were noted on porous substrates and no significant pyrophoric response was generated on the spin-coated, non-porous substrates. It is believed that this lack of response is due to the amount of material coated on the surface of the steel substrate and the high thermal conductivity of the steel substrate causing the quenching of the oxidation reaction from heat loss.
Thus a need exists for safer, environmentally benign, and more efficient methods for preparing pyrophopric materials that provides the same performance standards as current iron coated on steel pyrophopric decoys.